Good suspension expertise is hard to come by - but if you're making any modifications from stock, its well worth the effort to find it.

I'm lucky to have a local shop less than 100 miles from me here in Atlanta - but I'd ship my forks to a professional if I needed to. Among the options out there, I'd recommend RaceTech in California. http://www.racetech.com/ They stock parts for your bike.

Racetech owner, Paul Thede, wrote a book called the Motorcycle Suspension Bible - well worth reading before getting started.

There may be Service Information Bulletins that apply to your forks - there were some changes to fork seals, etc.

Before spending money buying new parts - I'd also recommend having your fork tubes inspected for straightness and surface imperfections - and your sliders inspected for wear.

There are several advanced things you can do to improve your forks such as having cartridge emulators installed to provide fast and slow damping, and having your sliders hard anodized to reduce friction. If you're working with an expert, they'll know about these things.

BMW forks in the 70's and 80's aren't adjustable - perhaps because they didn't trust an owner to make them worse my adjusting them improperly. While I've modified my forks on my older bikes (R100 and K100) the stock forks work pretty well for average riders in average conditions. I weigh in at 250 pounds - so I need beefier springs and better damping - and I ride pretty hard. Back in the 80's when I owned a new R100RS and weighted 160 pounds - I needed better shocks, but the forks worked just fine with only a fork brace and top triple clamp mod.